The present invention relates to a gas feeding system, and more particularly, to a gas feeding system for chemical vapor deposition (CVD) reactor capable of improving the uniformity and quality of deposited film in the manufacture of semiconductor devices. The present invention also relates to a method of controlling the same which prevents the waste of reactant source.
It is often desirable to form films of uniform thickness on a substrate in semiconductor manufacturing. Accordingly, considerable efforts have been made to improve both equipment and manufacturing process.
Recently, many processes for forming a high quality film were developed using surface reaction on a semiconductor substrate: processes such as using discontinuous supplies of a reactant source on a substrate, atomic layer epitaxy, and sequential supplies of a reactant sources on a substrate. The films formed by the above processes have enhanced uniformity and quality, and minimized impurity concentration therein, However, the above processes have a disadvantage of the waste of non-use and idling gaseous reactant sources.
In most conventional processes, one or more types of reactant sources were simultaneously and continuously supplied into a reactor, forming a film on a semiconductor substrate by the decomposition of reactant sources. However, such processes also have disadvantages that uniformity in film thickness, film quality, and impurity concentration are considerably affected depending upon the flow direction, flow velocity, temperature, types of used reactant sources.
Accordingly, it is an object of the present invention to provide a gas feeding system for chemical vapor deposition reactor and method of controlling the same capable of producing a high quality film when used for such process as using discontinuous or sequential supplies of a reactant sources.
It is another object of the present invention to provide a gas feeding system for chemical vapor deposition reactor and method of controlling the same capable of preventing the waste of non-use and idling gaseous reactant sources when not feeding the sources into the reactor.
In order to accomplish the aforementioned objects, the present invention provides a gas feeding system for chemical vapor deposition reactor having at least one reactant source supply apparatus, the supply apparatus each comprising: a mass flow controller for controlling the flow rate of a carrier gas which carries a reactant source; a reservoir for containing the reactant source, the reservoir having inlet and outlet valves for controlling the flow of the carrier gas through the reservoir; a supply valve for controlling the mass flow of the reactant source carried by the carrier gas to the reactor; an evacuation valve disposed between the outlet valve and the supply valve, the evacuation valve evacuating the carrier gas or the reactant source toward a vacuum pump; and a pass valve disposed between the inlet valve and the outlet valve so that the carrier gas passing therethrough flows into the reactor or the evacuation valve, the pass valve stabilizing the carrier gas mass flow controller as well as preventing the leakage of the reactant source from the reservoir.
In the embodiment, the number of the reactant source supply apparatus can be more than one, the supply apparatuses respectively having reservoirs containing different reactant sources, each of the supply apparatuses being connected to the reactor to supply different reactant sources therein in order to deposit complex materials such as PZT, BST, or SBT.
Preferably, the reactant source supply apparatus further comprises a first purge gas supply unit disposed between the supply valve and the reactor so as to prevent the backward flow of other reactant sources into the source supply apparatus upon deposition reaction. More preferably, the first purge gas supply unit further comprises a mass flow controller for controlling the flow of purge gas therethrough to a constant level.
In addition, the reactant source supply apparatus further comprises: a second purge gas supply unit disposed between the supply valve and the reactor so as to purge the reactant source residue; and a purge valve for regulating the flow of purge gas therethrough.
The present invention method is applicable to the control of a gas feeding system for chemical vapor deposition reactor having at least one reactant source supply apparatus, the supply apparatus each comprising: a reservoir for containing said reactant source, the reservoir having inlet and outlet valves for controlling the flow of the carrier gas through the reservoir; an evacuation valve disposed next to the outlet valve, the evacuation valve evacuating the carrier gas and the reactant source toward a vacuum pump; and a pass valve disposed between the inlet valve and the outlet valve.
The control method comprises the step of shutting off the inlet and outlet valves simultaneously with opening the pass valve so that the carrier gas passing therethrough flows into the reactor or the evacuation valve without the waste of reactant source in the reservoir.
In the control method, preferably, reactant source residue is removed by flowing the carrier gas into the reactor through the open pass valve. Additionally, the carrier gas is evacuated through the evacuation valve to stabilize the reactant source supply prior to the supply of reactant source from the reservoir to the reactor.
The foregoing, and other features and advantages of the invention, will be apparent from the following, more particular, description of the preferred embodiments of the invention, the accompanying drawings and the appended claims.